A new procedure to separate the instrumental and atmospheric components of stray light is presented. It is based on the dependence of the aureole's atmospheric component on the air mass and is applied to measurements taken with the Vacuum Newton Telescope (VNT) at the Observatorio del Teide (Tenerife). The resulting instrumental part is independent

Although spiral structure in grand design galaxies is generally present in the young and old stellar components and also in both atomic and molecular gas, the issue of whether the spiral structure is merely "organized" by a density wave, or whether star formation is triggered preferentially in the arms is still an open question. Here we present

EL FIN PRINCIPAL DE LA SISMOLOGIA ESTELAR ES OBTENER INFORMACION ACERCA DE LA ESTRUCTURA DE EQUILIBRIO DE LAS ESTRELLAS A PARTIR DE LAS FRECUENCIAS DE SUS MODOS PROPIOS DE OSCILACION. EN ESTE TRABAJO SE HA CONSIDERADO PRINCIPALMENTE LA INFLUENCIA DE LAS CAPAS MAS ALTAS DE LOS INTERIORES ESTELARES EN LAS FRECUENDE LOS MODOS P, HACIENDO UN ESTUDIO

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Two sources selected from the IRAS Point Source Catalogue (PSC) have been spectroscopically identified as galaxies with a Seyfert type active nucleus. The brightest of the first source, IRAS 20210 + 1121, is in close interaction with a companion galaxy at a projected distance of 1.1 kpc and has a perturbed spiral-like morphology. This galaxy

A new method to measure the magnetic field strength of small-scale solar magnetic concentrations is presented. It is based on the center of gravity method (Semel, 1967), is independent of radiative transfer calculations and only observable parameters are needed. This method also provides parameters like filling factor (area fraction occupied by the